(a) Field of the Invention
The present invention relates to a synthetic resin tube for guiding a rod-like medical instrument such as a catheter and a guide wire into, for example, a blood vessel and for keeping the medical instrument attached to the blood vessel.
(b) Description of Prior Art
A flexible tube of synthetic resin is generally used for guiding, for example, a catheter into a blood vessel and for keeping the catheter attached to the blood vessel. As shown in FIG. 1, a guiding tube 1 is mounted to a syringe 2 such that the tip of an inner needle 3 of the syringe 2 projects outward through the tip of the guiding tube 1. Then, the inner needle 3 is inserted into a blood vessel 4 until the tip of the guiding tube 1 is positioned within the blood vessel 4, as shown in FIG. 2. Under this condition, the inner needle 3 is withdrawn from the blood vessel 4, with the guiding tube 1 kept attached to the blood vessel 4. Further, a desired catheter 5 is inserted into the guiding tube 1 until the tip of the catheter 5 is positioned within the blood vessel 4, as shown in FIG. 3. After the catheter 5 has been attached to the blood vessel 4 as desired, it is desirable to withdraw the guiding tube 1 from the blood vessel 4 and from the catheter 5. It is sanitarily undesirable to leave the guiding tube 1 in the vessel after use. Also, the guiding tube, left unremoved after use, hinders the operation of the catheter 5. However, the presence of an enlarged portion, such as a connector 6 of the catheter, makes it quite difficult to withdraw the guiding tube 1 from the catheter 5.
Several measures have been proposed to date for withdrawing the guiding tube 1 from the catheter 5 after use. For example, it has been proposed to provide the guiding tube with a longitudinal slit to enable the guiding tube after use to be readily removed from the catheter. However, serious problems result. For example, the strength of the guiding tube is lowered, making it troublesome to operate the guiding tube. Also, the slit of the guiding tube is likely to expand when the catheter is inserted through the guiding tube into a blood vessel, leading to a leakage of blood. To overcome this problem, unavoidably the slit must be made narrow, with the result that removal of the guiding tube from the catheter is difficult.
Japanese Patent Disclosure (Kokai) 56-11069 proposes another measure. Specifically, it is proposed that a guiding tube is provided with a pair of linear bodies extending along the length of the guiding tube and positioned opposite to each other in the radial direction of the guiding tube. The linear body is formed of a plastic material foreign to the material forming the main body of the guiding tube. Also, the proximal end portion of the guiding tube, which is joined to the inner needle hub, of the guiding tube is provided with a pair of slits aligned with the linear bodies. After a catheter or the like, inserted through the guiding tube, has been attached to a blood vessel, the proximal end portions of the guiding tube are pulled outward in opposite directions. As a result, the guiding tube after use is split into two parts along the linear bodies. Of course, the slits formed in the proximal end portion of the guiding tube facilitate the splitting. In this proposal, however, the linear body tends to crack during post production treatments, such as cutting or edge-processing of the guiding tube, or during transport or the like of the product guiding tube, with the result that is used leakage of blood is likely to take place so as to make the guiding tube unsuitable for use.